Many consumer packaging applications employ reclosable bags. These bags employ reclosable zippers for locking products within the bags. A typical reclosable zipper includes male and female closures extending along the entire length of the zipper. The male closure typically may be tree-shaped, with an expanded head portion supported by a narrower trunk portion. The female closure is disposed opposite to the male closure and is adapted to mate with the male closure by members having locking edges or cornered shoulders. The closures are interlocked by properly aligning the male and female closures and pressing the closures together along the entire length of the zipper. The opposed members of the female closures slide over the expanded head portion of the male, and lock to it by hooking the head with the cornered shoulders and resting in the trunk portion.
In some applications, it is preferable to increase the "holding" or "lock" strength of the reclosable zipper to ensure that the zipper will not accidentally reopen, releasing the contents of the bag, and to also ensure an airtight seal between the inside of the bag and the outside of the bag. To increase lock strength, existing reclosable zippers employ stiffer materials or different configurations for designing the locking members of the zipper closure. Stiffer materials increase lock strength because such materials do not "give" as easily as more flexible materials, thereby making it more difficult to disengage interlocked locking members.
In order to increase the sealing properties between the male and female closures, it is sometimes advantageous to increase the surface area of the male and female closure which come in contact with one another. This increase creates a wider more resilient seal. Some of the prior art closure arrangements include male and female profiles with sharp angles or turns. In those cases, the surface area is reduced, and the sealing properties are not optimal.
In many consumer packaging applications, it is important to prevent air or water or the like from passing out of or into a package containing certain products. This is particularly true with respect to meat packages, cheese packages, and the like, for which the contained product is kept in a constant environment to prevent spoilage. In order to preserve the product contained within such a package, the periphery of the package is hermetically sealed. Hermetic seals can be provided by both permanent seals and temporary seals known as break-away seals. Break-away seals are capable of providing a hermetic seal and, at the same time, provide a consumer with access to the contents of a package. A break-away seal provides an indication of whether the package has been previously opened. Once the seal is broken by a consumer to initially gain access to the contents of the package, it cannot be restored.
To provide a break-away seal on a package with a reclosable zipper, the package typically uses permanent seals at its side edges and bottom edge and a break-away seal at the mouth end of the bag. Traditionally, the break-away seal at the mouth end of the bag has been positioned either adjacent to the reclosable zipper at the mouth end of the package or in gaps between the male and female locking members of the reclosable zipper.
When arranged adjacent to the reclosable zipper, the break-away seal may be positioned either above or below the reclosable zipper on the flange/skirt thereof. Positioning the break-away seal on the skirt of the zipper is disadvantageous because the skirt must be wide enough to accommodate the break-away seal. Such a wide skirt increases the amount of polymeric material required to form the zipper and, therefore, increases the cost of producing the zipper. Also, the increased amount of polymeric material can result in a higher incidence of leaks at the edge of the zipper, because an increased mass of polymeric material must be cut through, which can distort the zipper cross section upon cutting.
In an effort to overcome the above-noted shortcomings associated with positioning the break-away seal on the skirt of the zipper, it has been taught to arrange the break-away seal in gaps between male and female locking members of the reclosable zipper. When arranged in gaps between male and female locking members of the reclosable zipper, the break-away seal may be located, for example, between a T-shaped head of a male locking member and a base of a groove formed by two female locking members. One disadvantage of such a break-away seal is that it allows contaminants to travel up to the point of the break-away seal, which means that the locking members themselves can be contaminated prior to opening the bag.
Consequently, a need exists for a closure arrangement for a polymeric bag which overcomes the aforementioned shortcomings associated with existing closure arrangements.